Recently, unprecedented natural disasters have occurred domestically and internationally, and interest regarding countermeasures against disasters is growing more than before. To reduce the damage caused by such disasters, many cellular mobile communication systems quickly report the state of emergency to many users by simultaneously broadcasting urgent warning information such as earthquake early warning. Non-Patent Document 1 discloses such a broadcast communication service.
However, in a time of disaster, the cellular mobile communication system tends to have difficulties in providing communication services due to damage of base stations and network congestion and the like. On the other hand, a communication system performing digital terrestrial television broadcasting for mobile terminals can provide communication services relatively stably even in such a time of disaster. Therefore, a user of a mobile terminal that can receive a television signal can receive urgent warning information from the television signal even in a time of disaster. However, it is necessary that the mobile terminal is receiving the radio wave of the digital terrestrial television broadcasting for receiving the urgent warning information by the digital terrestrial television broadcasting. That is, the mobile terminal needs to be activated so as to be able to receive the digital terrestrial television broadcasting. Thus, there is a fear that consumed power of the mobile terminal becomes very large. This point is different from the cellular mobile communication system in which the terminal can receive simultaneous broadcasting of urgent warning information even in a standby mode.
In view of the above-mentioned problem, in the invention described in the patent document 1, a mobile terminal with a TV receiving function starts the TV receiving function to receive urgent broadcasting when the mobile terminal receives an e-mail or when the mobile terminal goes out of the range of communication.